I wait til the plants are well established bedding size, but not hardened off totally yet. I usually bring my plants out when the temps are usually above freezing. If the temps are forecasted for below, then I cover with row cover, sometimes more than 1 layer. I found out last year that 3 layers can save tomato plants down to about 26 degrees with high tunnel at 34 and outside in the teens.

Thanks. I have some broccoli that will be ready soon, or I'll have to move up to bigger pots. I'm trying to figure out a reliable way to get spring broccoli. It's hard to get it in early enough to make a head and not bolt. I've been decently successful with fall plantings.

I would expect it's much harder in zone 7 to have broccoli early versus zone 5. You could probably direct seed it, I can almost.

Vicki,
It's just my opinion but it seems too early for broccoli. I'm in zone 8b, so i'm not sure exactly for your area, but I don't seed spring broc till the beginning of March. It transplants a month later and I have beautiful heads most of June into July (when aphids start).
Do other growers in your area start it this early? I'd think light levels are nowhere near adequate for good growth.

If this timing is actually right for your area, i'd think the main factor for small heads and early bolting is not enough fertility. Broc is a heavy feeder, especially when the soil is cool and not moving nutrients easily.

-Mark

I would not bother transplanting spinach as it hates to be transplanted and will germinate in 40F degree soils. We usually will start direct seeding outside of tunnels in mid to late March (this depends on if the soils are not snow covered and thawed-sometimes we can plant in Feb some years we wait until mid April). A soil thermometer would be helpful for you so you know when the soil temps are warm enough to start planting.

While you have a lot more day light than Oregon we are still under 12 hours and that is cutting it close for broccoli which needs at least 4 hours of direct sunlight and I believe at least 11 hours of day light. The big trick I find for broccoli is never ever let it get root bound before transplanting which means for me no more than 4 weeks in soil blocks before going into the field. When they get root bound as seedlings they will almost always give you button (small) heads.

If you transplant into the low tunnels you should be able to plant a good 4 to 8 weeks before your last frost. We do this all the time in Ohio with row covers and with our small hoophouses/high tunnels.